Electron discharge device



June 1940. M. J. o. STRUTT :1- AL 2,205,500

ELECTRON DI SCHARGE DEVICE *3 jhm -m- L24 2/ IINVENTORS MAXIMILIAANJ.O.STRUTT BY a P TRUS H.J.A.KLEYNI'-IN fl w ATTORNEY.

J1me 1940. v M. J. o. STRUTT El AL 2,205,500

ELECTRON DISCHARGE DEVICE Filad Nov. 24, 1937 3 Sheets-Sheet 2 INVENTORSMAXIMILIAAN J.O.STRUTT 8. P TRUS H.J.A.KLEYNEN W @QJQW M ATTORNEY.

June 25, 1940- M. J. o. STRUTT Er AL 2,205,500

ELECTRON DISCHARGE DEVICE Filed Nov. 24, 1937 3 Sheets-Sheet 5 INVENTORSMAXIMILIAAN J.O.$TRUTT 8' P RUS A.KLEYNE| ATTORNEY.

axis of the cathode.

Patented June 25, 1940 ELECTRON DISCHARGE DEVICE Maximiliaan J.- 0.Strutt-and Petrus H. J. A. Kleynen, Eindhoven, Netherlands, assignors,by mesne assignments, to Radio Corporation of America, New York, N. Y.,a corporation of Delaware Application November 24, 1937, Serial No.176,174

In Germany November-.26, 1936 6 Claims.

This invention'relates to a device comprising an electric discharge tubehaving a cathode, an anode and two or more other electrodes, one ofwhich consists only of a few rods or slat portions,-

and in which the electrons emitted by the cathode are united intobeams,'the grid-voltage anode current characteristic curve beingdetermined by influencing the dimensions of the beam.

The principal object of the invention is to provide an electrondischarge device which can be built easily and in a comparatively simplemanner to have the desired characteristic curve.

In accordance with the present invention, the electrons issuing from thecathode are concentrated in radial beams by rod or plate-shaped membersarranged parallel with the longitudinal axis of the cathode,'and meansat the ends of the electrode system afie'ct the form of the radial beamsin a direction parallel with the longitudinal In this way the spot to becast on the anode can be given any optional form.

In one form of tube constructed according to the present invention anintercepting electrode is mounted in front of and close to the anode,and so shaped that; in combination with the beam-shape, a characteristiccurve is obtained having the desired form in adefinit'e case. I

The end electrodes which extend in a plane substantially normal to thecathode, may be plateshaped or sheet electrodes and may be connected toa point of'constant' potential, for instance to the cathode or'toanother'point of constant or negative potential or to a variablevoltage, so that variations of the voltageaffect the electrostatic fielddue to the end electrodes and cause a variation in the widthof the beamin a direction parallel with the cathode and consequently in the shapeof the beam. One or more additional grids maybe provided between thecontrol grid and the intercepting electrode, one of which additionalgrids may act as a protective grid, although the functionsof theintercepting electrode and of the protective grid may be united in oneelectrode. The invention may be used with pentodes and octodes whereinan additional pentode suppressor grid is provided between theintercepting electrode and the anode. The invention will be more clearly.understood by reference to the accompanying drawings in which, by wayof example, various, forms of embodiments of the invention are shown andin which Figures 1 and 2 are longitudinal sections of mounts oftubesembodying the invention, Figure 3 is the forrnof the anode spotobtained with tubes constructed as shown in'Figures 1 and 2, Figures 4and 5 are longitudinal sections of other modifications, Figure 6 is across-section of Figure 1 along the section line 6- -6, Figures '7 and 8are longitudinal sections of other modifications, Figure 9 shows-theanode spot produced bytubes constructed as shown in Figures '7 and 8,Figure 10 shows a mount partly in longitudinal section of still anothermodification, Figure 11 is the anode spot produced by the tube showninFigure 10, Figure 12 is a plan view of the screen grid with which astraight characteristic curve can be obtained, Figure 13 is a plan Viewof a screen grid by which an exponential grid voltageplate currentcharacteristic curve may be obtained, Figure 14 is a developed view ofthe anode,

of the tube shown in Figure- 10, and Figure 15 shows the anode spotproduced by tubes constructed as in Figures 4 and 5. l

In Figures 1 and 2 the mount comprises a press l,which carries, anelectrode system comprising a rectilinear cathode 2, preferably of theindirectly heated type, a control grid 3 consisting'of rods parallel tothe longitudinal axis of the cathode and a tubular anode 4 surroundingand coaxial with the cathode and the control grid. By the effect of thecontrol: grid voltage the electron discharge from the cathode to theanode is concentrated or united into electron beams which are flattenedand are in general rectilinear in cross-section with the width of thebeam extending lengthwise of the cathode. Between the beam formingcontrol grid and the anode is mounted an aperturedintercepting'electrode or anode 4a with an aperture 4bin the path of theelectron beam. The form of the aperture in the inter cepting electrodein combination with the shape of the electron beam detern'iines theshape of the anode spot and the shape of the characteristic curve of thetube. The shape of the electronbeam formed by the control grid 3'isafiected and determined by end members such as the sheet electrodes ordiscs 5 and the rod electrodes 6 in Figures 1 and 2, which are mountedat the oppo-' site ends of the electrode system so as to extend inplanes normal to the cathode. By impressing voltage on these end members5 and 6 an electrostatic field is produced which will afiect the beamshape in a direction parallel with the longitudinal axis. of the,cathode. Tubes constructed as shown in Figures 1' and 2 will produceananode spot. illustrated in Figure 3 and the form of this spot varieswith variation in voltage of the control grid and of the end members.The

Figure 1. An input transformer 20 has connected to one side of its tunedsecondary the lead to the control grid 3 and its other side connected tothe anode voltage supply 2|. The end plates 5 and the end control rods 6may be connected to the grid side of the secondary of the transformer bymeans of conductor 22 and adjustable tap 23 or they may be connecteddirectly to the grid lead as indicated by the dotted line.

ply source.

plane of beams produced by control grid 3. This of the input transformerand, therefore Vary in potential with variations in control gridvoltage.

When the control grid voltage is high, the anode spot, as illustrated inFigure 3, has the form or outline ll. As the control grid voltagedecreases, the anode spot shrinks to the form [2, and at still lowercontrol grid voltages, shrinks to the form l3.

Figures 4 and 5 show a modification in which the end members foraffecting the shape of the electron beam in a direction parallel to thecathode are in the form of rods 1 located at opposite ends of theelectrode system and by a rigid metal connector Ia to the control grid 3and carried by it if desired, although they are shown provided with aseparate support and lead.

Figure 15 shows the form of the anode spot produced by the tube shown inFigures 4 and 5, the anode spot having the form II at high grid voltagesand shrinking first to the form l2 and then to the form l3 as thecontrol grid voltage is lowered. The effect of eliminating the endplates 5 is shown in Figure 15 where wider and longer legs appear at thetop and bottom of the spot shown in Figure 11. The reason for this isthat the beam is compressed only by the field of the rods I in the pathof the beam, whereas in the construction shown in Figures 1 and 2 boththe shields 5 and the end rods 6 exert an in-, fiuence on the shape orthe beam and have a greater compressive action than the rods 1 alone.The construction of the tube shown in Figures 4 and 5 is simpler thanthat shown in Figures 1, and 2' and in the resulting anode current thedifierence between maximum and minimum cur: rent is greater. Figures 7and 8 illustrate a modification in which the end members are sheets ordiscs 8 at opposite ends of the electrode system, these end membershaving a separate connction by which any desired voltage may beimpressed'upon the end members. When the end members are cone nected tothe control grid, the anode spot, as shown in Figure 9, isin general,similar to that obtained from the tubes shown in the preceding figures,the spot having the form I l at high con,- trol grid voltage, andshrinking to the forms l2 and I3 in succession as the control gridvoltage is lowered.

Figure 10 is a longitudinal section ofa modi fication in which the sheetordisc end members .8 are similar to those shown in Figure 7; the anodesHare in the developed state of the form illustrated in-Figure 14 so asto provide two The output :is fed to the transformer 24. If desired, theend plates 5 could be connected to the cathodef'The'" interceptingelectrode or anode 4a is connected to.

an intermediate point on the anodevoltage sup-.

It will be noted that the end rods 6 extend normal to the cathode andlie in a median diametrically opposite slots or apertures in the path ofthe electron beams from the cathode, and are surrounded by an electrode10. When the end members 8 of the tube shown in Figure 10 are connectedto the cathode, preferably by a connection 8a inside the tube, the anodespot obtained has the form shown in Figure 11. With these connections,the anode spot at high con- ..tro1 grid voltage is of the substantiallysquare form H and as the grid voltage is lowered, the

" spot shrinksto the rectangular forms l2 and I3.

The anodes 9 couldbe replaced by cylindrical anodes having aperturesshaped like the anodes shown in Figure 14. In this case the aperturedelectrode would serve as the intercepting electrode, the apertures ofcourse lying in the path otthe beam from the cathode 2. It is alsopossible in the construction shown in Figure 10 to provide the electrodeIll with a surface which will promote secondary emission, the secondaryelectrons returning to the anodes 9. If desired, the electrodes 9 couldbe replaced by intercepting electrodes made of gauze, properly treatedto promote secondary emission for increasingthe output to the electrodeIll.

The intercepting electrode between the control grid. 3 and the anode 4may take the form of a screen grid having a specially shaped aperturefor determining the shape of the characteristic curve. Figure 12 shows ascreen grid with an hour glass shaped aperture [5 covered by a wiremeshand by means of which in conjunction with the mount structure shownin Figure 10 a straight characteristic curve can be obtained. Figure 13shows a screen grid in which the aperture I6 covered by a wire mesh andof the generalanode, a beam forming electrode adjacent said; cathode andconsisting of spaced conductors substantially parallel with thelongitudinal axis of the cathode for concentrating the electrondischargefrom the cathode into a flattened radial beam with its Widthextending lengthwise of the cathode, intercepting electrode adjacentsaid beam. forming electrode and between said beam forming electrode andsaid anode, said intercept-r ing electrode having in the path; of thebeam an aperturelsmaller than the normal cross-sectional areaof thebeamat said intercepting electrode, and means at the opposite ends oi-theelectrode system for producing an electrostatic field to vary the widthof the electron beam in a direction parallel with the longitudinal axisof the cathode. 2. A device as defined in claim 1 in which the cathodeis indirectly heated and the means for producing an electrostatic fieldcomprises end electrodes mounted at the ends of the electrode system andextending in a plane normal to the cathode 'and connected to thecathode.

3. An electron discharge device comprising an elongated cathode, acontrol grid comprising a pair of spaced conductors mounted parallelwith and on opposite sides of said cathode to produce a sheet electronbeam extending lengthwise of and radial to said cathode, end electrodesat opposite ends of said cathode extending normal tofsaidcathode and tothe plane of said rods, means electrically connecting said endelectrodes to said control grid, an anode surrounding said cathode andcontrol grid, and an intercepting member between said anode and saidcontrol grid having intermediate its ends and in the path of said radialbeam an aperture narrower than the normal width of said beam in adirection parallel to said cathode.

4. An electron discharge device having an electrode system comprising arectilinear cathode, a beam forming electrode adjacent said cathode forconcentrating the electron discharge from the cathode into a flattenedradial beam with its width extending lengthwise of said cathode,twojuxtaposed anodes of different diameters surrounding and coaxial withsaid cathode, the inner one of said anodes having in the path of saidelectron beam an aperture with its Width extending lengthwise of saidcathode and less than the normal width of the beam at said inner anode,end electrodes mounted at opposite ends of the electrode system andprojecting in planes substantially normal to said cathode and along theedge of said electron beam on opposite sides of the aperture in saidinner anode and means for connecting said end electrodes to said beamforming electrode. j

5. An electron discharge device comprising a rectilinear cathode, ananode surrounding said cathode, a beam forming electrode adjacent saidcathode for concentrating the electron discharge from said cathode tosaid anode into a flattened beam radial to said cathode and with itswidth parallel to said cathode, end electrodes at opposite ends of saidelectrode system extending substantially perpendicular to said cathodeand said beam forming electrode and parallel to the edges of the radialelectron beam, means conanode consisting of two elongated spacedconductors parallel with and on opposite sides of the cathode to formthe discharge from said cathode to said anode into a sheet beam radialto said cathode and with its width parallel to said cathode, two endelectrodes electrically connected to the control electrode inside thetube and mounted at the opposite ends of the electrode system to extendin planes normal to the cathode, and an intercepting electrode betweensaid beam forming electrode and said anode having in the path of saidbeam an aperture narrower than said beam. I

MAXEMILIAAN J. O. STRUTT. PETRUS H. J. A.' KLEYNEN.

